Waterproof silica-base greases



United States Patent No Drawing. Application December 7, 1955 Serial No.551,509

4 Claims. (Cl. 252 -28) This invention relates to the thickening ofoleaginous liquids by means of finely divided, inorganic gelatinousmaterial. It is especially directed to the preparation ofwater-resistant lubricants comprising an oleaginous vehicle thickened toa grease-like consistency with a nonsoa'p inorganic gelling agent foruse in high temperature applications.

Although lubricating greases by ASTM definition are the shortage ofconventional grease-making components. Greases employing inorganicgelling agents: can be prepared in the standard type of grease makingequipment without requiring runusual processing conditions. Although thegreases thickened with inorganic gelling agents are suitable formulti-service duty, their resistance to changes in consistency over awide temperature range makesthem very desirable compositions for hightemperature applications. While the consistency of soapthickened greasesat elevated temperature is inimicably aifected, greases thickened withinorganic gelling agents retain their grease structure. If working ofthese greases has occurred, the base oil may distill or even ignite, but

no melting of the grease results. Unfortunately, these multi-purposegreases do not present an ideal solution to lubricating problemsinasmuch as one serious deficiency in greases thickened with inorganicgelling agents is demonstrated by their lack of water resistance. Thischaracteristic is fatal because exposure of a simple admixture of silicaand oil to Water results in the rapid disintegration of the mixture intoits component parts.

semi-solid. or solid combinations of a petroleum prod-f.

net and a soap or amixture of soaps, there have been developed a numberof compositions which do not employ petroleum oils as the baseconstituent and a number of thickeners for these base liquids which arenonsoap gelling agents, but can be used in the preparation of? thickenedcompositions which functionally are the equivalents of a true;lubricating grease. Furthermore, thelubricating compositionsthusprepared have properties in" which soapcontaining petroleum baselubricating greases are generally deficient. In spite of the fact thatthe compositions of this invention do not conform with the "conventionaldefinition of a grease, they will hereinafter be included in thiscategory in order to facilitate the discussion of the instant invention.

Inorganic colloids capable of gel formation in oleaginous vehiclesinclude alkali-ne earth metal oxides and hydroxides; carbonates ofalkali metal and Iaikaline earth metals, ferric oxide, vanadiumpentoxide, oxides and hydroxides of. polyvalentmetals, such as silicon,magnesium, aluminum, tin, chromium, etc.; sulfides of polyvalent metalsqincluding cuprous sulfide, ferrous sulfide, and others. Thepreparationof inorganic colloidal thickenirrgagents iscomprehensivelydiscussed in. the patent literature: For examples, seeUS. Patents 2,260,645, 2,583,603-4, 2,554,222, 2,594,822, 2,629,691.,and others. Also included are the siliceous gelling agents prepared bypyrolyzing silicon compounds, such as silicon tetrachloride, tetraethylsilicate, or a chlorosilane to produce finely divided materials.Examples of this type of gelling agent are. theCab-O-Sils marketed bythe Godfrey L. Cabot, Inc. M

Anon-soap gelling agent which has found considerable application in thepreparation of lubricating greases is finelydivided silica. Accordingly,the following discussion is directed. to a description of greasesprepared by the use ofthis material. However, this is only illustrativeand non-limiting. This material, when dispersed in a suitable liquidmedium including petroleum oil lubricating fractions, will produce agelatinous composition with a greaseelikestructure having lubricatingproperties. i 'The "development of inorganidgell ing agents apparentlyorigipated in Germany during World War II as a solution. to

It has been found, however, that by treating the gelling agents employedin the preparation of lubricating greases with suitable reagents, theinorganic gel-oil composition can be stabilized against the detrimentaleifect of 'Water. Improvement in the water resistance is effected bycoat ing the inorganic gelling agent or by using suitable additives inthe lubricating :grease. Boner, in Manufacturing and Application ofLubricating Greases, Reinhold,..1954, at page704 et seq.,comprehensively discusses the modification of silica gel to increasewater resistance based on a compilation of the prior art.

Various methods are employed to evaluate the resistance to breakdown ofthe grease structure in the presence of water. One technique involvesthe addition of incremental amounts. of water with subsequent mixing ofthe water-lubricant system, and observation of the accompanying changein grease structure, if any. Another test immerses a sample of thegrease, retained in a suitable specimen holder, into boiling water foronehalf hour. Apparently a more rigorous procedure for determining thewater resistance of a grease of this nature is the test method ASTMdesignation: D1264-53T, described in the 1953 Supplement to Book of ASTMStandards, Part 5, ASTM. In this method the grease sample is retained ina rotating ball bearing and subjected to the washing action of distilledwater for 1 hour at specifled test temperatures. It has been foundthatwaterproofing agents generally considered adequate for imparting waterresistance to water-susceptible greases prepared from inorganicIgelli-ng agents are unsatisfactory for making a greasecompoistion'which will give satis factory results, when subjected to thescrutiny of the aforementioned ASTM method for determining the waterwashout characteristics of a lubricating grease.

It is therefore an object of this invention to provide a non-soapthickened lubricating grease having enhanced 'water resistance. Anotherobject of this invention is the production of a lubricating greasehaving improved resistance. to water washout. It is also an object ofthis invention to improve the water washout characteristics ofaIsilica-thickened lubricating grease. These and other objects willbecome apparent from the following detailed description of thisinvention. r t p According. to this invention, it has been found thatorder to provide a non-soap-thickened lubricating grease havingexcellent resistance to water washout, it is necessary to incorporate inthe grease composition a combination waterproofing additive comprisingan admixture of (1) an oil-soluble alkylaryl polyether alcohol preparedby condensing an alkyl phenol and ethylene oxide, and (2) an oil-solublealiphatic monoether or polyoxyalkylene glycol prepared by the additionof a monohydroxy aliphatic alcohol to 1,2-propylene oxide.

In formulating the grease composition 4 ration of suitable compositionsare reported in U.S. Patent 2,448,664. Although a variety of monohydricaliphatic alcohols can be employed in the reaction, preferredcompositions are prepared by reacting butanol and 1,2-propylene oxide.By varying the molecular weight of the addition product, changes inproduct characteristics are obtained, as shown in Table I, wherein aretabularly summarized the properties of proprietary compositions of thisnature marketed by Carbide and Chemicals of this inven- Corporationunder the mark Ucon.

TABLE I Properties of Ucon brand lubncants-LB series LB140 LIB-300LB-400 LB-550 LIB-650 Viscosity, SUS at: i

Viscosity, centistokes at:

50 F 58, 000 300, 000 510, 000 850, 000 VI. (ASTM D 147 142 142 140 140Your Point (AS 50 -40 -85 ---30 25v Density at 210 F g per cc 0. 9210.933 0. 936 0.939 0.940 Density at 100 F., g. per cc 0. 966 0. 9790.983 0. 985 0. 980 Specific Gravity at 60 F..- 0.983 0. 997 1. 001 1.003 1.004 Gravity, deg. API at 60 F 12. 5 10. 5 9. 7 9. 5 9.4 FlashPoint (AS'IM D-92-33), F 440 470 485 510 625- Fire Point (ASTM D-92-33),F 510 57 580 580 680 Carbon Residue (ASTM D-189-41), percent... 3 p

- Ash (ASTM D-482-43-T), percent 1 Less than 0.01.

tion, a suitable inorganic gelling agent such as those described above,preferably silica aerogel, which has been prepared according to themethod of Kistler in U.S. Patent 2,260,625, is incorporated in aselected oleaginous vehicle including conventional mineral lubricatingoils of Pennsylvania, Mid-Continent, Gulf Coast, East Texas, California,etc. origin. Other oleaginous bases may also be employed, such assynthetic lubricating oil derived from the polymerization of olefiniccharge stocks; aliphatic and aromatic esters, viz., aliphatic esters ofdicarboxylic acids, e.g., dioctyl sebacate; organic phosphates, e.g.,tricresyl phosphate; silicone oils, and other oleaginous liquidpossessing satisfactory lubricity characteristics. To impart to thefinished grease satisfactory water washout resistance, the waterproofingadditive of this invention is admixed with the oil-thickener blend. Thisoil-soluble additive consists of a combination of (1) an alkyl arylpolyether alcohoLand (2) an aliphatic monoether of a polyoxyalkyleneglycol. I

The polyether alcohol constituent of the water-proof- 'ing additive isprepared by condensing an alkyl phenol wfih ethylene oxide to form anoil-soluble producthaving a molecular weight of about 200-650. Phenolshaving C C alkyl substituents, such as di-isobutyl phenol, octylphenol,;nony1 phenol, octadecyl phenol, tridecyl phenol, dioctyl phenol,and others, or mixtures thereof, can be condensed according toconventional techniques with ethylene oxide to provide polyetheralcohols of molecular weight suificient to impart oil solubilitycharacteristics to the polyether alcohol. An example of a preferredalkyl aryl polyether alcohol is Triton X-45, a

' proprietary compound marketed by Rohm and HaasCom- The otherconstituent of the waterproofing additiveis an oil-soluble aliphaticmonoether of a polyoxyalkyl'ene glycol which is synthesized by adding amonohy'drox'y aliphatic alcohol to propylene oxide. Details for prepa-For the compositions of this invention, it is preferred that thealiphatic monohydric alcohol-propylene oxide addition product having anaverage molecular weight of about 800-1600 (acetyl value) be employed.According to this invention, the combination of (1) an oil-solubleadditive product of an aliphatic monohydric alcohol and propylene oxide,and (2) an oil-soluble alkyl aryl polyether alcohol, in the ratio of 1to 15 parts by weight of the former to one part by weight of the latter,will improve the water washout characteristics of a non-soap thickenedgrease. It is preferred that a ratio of 4,-8:1 be employed to giveoptimum results. The amount of composite additive employed will dependupon the amount of gelling agent used. Generally, 9 to 10% by weight,based on gelling agent, will provide satisfactory results. However,amounts outside this range may be employed. In order to prepare afinished grease it may be necessary to add other functional additives toimpart to the finished grease corrosion and oxidation resistance,extreme pressure characteristics, etc. Table II shows illustrativeranges of ingredients. I

TABLE II Parts by Weight Component Suggested Preferred Liquid,oleaginous lubricating vehicle -96 88-94 Non-soap gelling agent 4-206-12. Water-proofing additiv 3- 0 .5-1.1. Functional additive, e.g.,rust inhibitor,

anti-oxidant, V.I. improver, E.P. agent. As required. As required.

I The subject invention is illustrated in a non-limited manner by thetabular summary of data shovvnfin Tab1e.III....: x

anemic TABLE III Composition, Wt., A B O D E F G H I J K L M N .PerceiitSilica Aerqgel IIhickener 9. 9. 0 9. 0 19:0 --9. 0 9. 0 9. 0 9. 0 9. 09. 0 9. 0 9. 0 9. 0 9.0 W erprooflngAgent: 1 -Aliphatio monoether .oipolyoxyalkylene gly- (:01 0. 72 0.74 0. 65 0. 80 0. 56 0. 92 0. 64;. ,0.80 Alkyl aryl polyether al- 1 i i .1 001101 3 0. 09 0. 074 0.16 0.050.18 1039. 0.108; 0.10 o: Aliphatic monoether of polyoxyalkylene glyl icol lalkyl aryl polyether 81001101 8 4 16 3.1 1,3- o -l--. :8= 8Waterproofing AgentX p p h 100 Silica Aerogel..- 9 9 9 9. 4 8. 2 10 7 55 7 "7 '10 "8' 10 ineral Lubricating Oil L.-- 90. 19 90.19 90.19 90.1690. 26 90. 08 90.37 90. 55 90. 55 90. 37 90. 37 90.1 90. 28 90. 10 reaseCharacteristics:

Penetration Unworked 2 49 235 237 233 239 241 250 255 238 249 248 249239 238 W0rked- 282 262 259 271 257 276 276 309 275 264 313 282 276 265Water Washout wt. i

percent grease loss n.-- 21 15 39 26 39 22 41 56 59 25. 2 84.1 60. 4 24.3

l santoc'el ARD, a proprietary silica arog'el marketed by MonsantoChemical Company, having a particle size of 3-5 microns in diameter, abulk density of 0056-0064 gmsJml. I

i UOON-LB 550, a proprietary composition marketed by Carbide and CarbonChemicals comprising an oil-soluble addition product of butanol and1,2-propylene oxide having an average molecular weight of about 1 4 3Triton X45 a proprietary compound marketed by Rohm and alcohols havingan average molecular weight of 338-514 and prepared by 00 (acetyl value)and having the characteristics shown in Table I. aas Company, comprisingan oil-soluble admixture of homologous polyethcr condensing di-isobutylphenol and ethylene oxide.

Intermediate V.I. bright stock mineral lubricating oil prepared byphenol extracting, MEK dewaxing, and clay contacting a Mid-Continentlubricating oil fraction, and having the following characteristics:

Viscosity, sUs at 210 16.4 Gravity, API 24. 5 Flash, F. (00C) 565 Fire,F. (O0C) 630 Viscosity Index 91 Pour point, F., ASTM 0 Color NPA(ASTML..- 7 Carbon residue, percent 1. Sulfur, percent 0. 80 Neut. No.(1) l 0.05 Ash, perr n 0.002

' ASTM Designation D 128-47. ASTM Designation D 1264-531.

The eifcctiveness of the instant invention for enhancing the waterwashout characteristics of a non-soap-thickened lubricating grease isfurther illustrated by comparison with a lithium soap-thickenedlubricating grease having the following composition:

Component Percent Lithium 12-hydroxy stearate Mineral oil base:

Intermediate V.I. (160 S.U.S. at 210 F./90 V.I.) Mid- Continentsolvent-refined, bright stock lubricating oil. High VI. (85 8.115. at100 F./95 V.I.) Mid-Continent,

solvent-refined, neutral lubricating oil Phenol extract of a brightstock lubricating oil fraction 1 A mineral oil lubricating fractionobtained as an extract from the phenol extraction of a dewaxed anddeasphalted Mid-Continent residuum and having the followingcharacteristics:

It will be seen that, by means of this invention, a non-soap-thickenedlubricating grease can be made, which will have water washoutcharacteristics comparable to a lithium soap-thickened lubricatinggrease, a composition to which is generally attributed good waterresistance, and is used as a multi-purpose lubricant. To furtherillustrate the advantages of the instant invention, a non-soap-thickenedlubricating grease was prepared without employing the compositewater-proofing.

agent of this invention. It was found that this grease had no resistanceto water washout and completely disintegrated under the water washouttest conditions.

I claim as my invention:

1. A silica-thickened grease having enhanced water washoutcharacteristics consisting essentially of a lubricating oil havingincorporated therein a finely divided silica gelling agent in an amountsufficient to impart a grease-like consistency to said lubricating oil,and a composite water-proofing agent consisting essentially of 4- 10parts by weight of (1) an oil-soluble mono-alkyl ether of apolyoxyalkylene glycol produced by reaction of a monohydric aliphaticalcohol and 1,2-propylene oxide having a molecular weight of 800-1600(acctyl value), and one part by weight of (2) an oil-solublemono-alkylaryl ether of a polyoxyethylene glycol produced by reaction ofa (l -C alkyl-substituted phenol and ethylene oxide having an averagemolecular Weight of 200-550, said waterproofing agent being present tothe extent of 9-10% by weight of the silica in an amount suflicient toimprove substantially the water-washout characteristics of said grease.

2. A grease composition in accordance with claim 1 in which thecomposite waterproofing agent contains 4-8 parts by weight of compound(1) and one part by weight of compound (2), said Waterproofing agentrepresenting about 9% by weight of the silica.

3. A silica-thickened lubricating grease composition consistingessentially of:

Components Parts by Weight 7 4. silica-thickened lubricating greasecompositien References Cited in the file of this patent essnflallyofiUNITED STATESPATENTVS v. l G t 1 H f b Z 2,573,650 Peterson Oct. 30,1951V 33gb; 2,652,365 Moore et a1. 'Sept'. '15, 1953 1 12,680,095 Hottenetal. 4:1 pm 1;; 1954 Mgne raglub rmatj g'nn 3' 2,739,121 Weihe *et a1.1 v Iay 20, 1956 g s g gggggf gg 9 Marshall et al. 'OCLw9p 1956 a. Anoil-soluble mono-alkyl ether oia olyoxyalkylene if I 3 V I glycolproduced by reaction of a mono ydric aliphatic alcohol and 1;2-propyleneoxide having amoleeular weight of 800-1,600 (acetyl value) 0.80 b. Anoil-soluble mono-alkyl aryl ester of polyoxyethylene glycol produced byreaction of a. 01-0 aJkyl-substituted phenol and ethylene oxide havingan average molecular weight of200-550 0.10

1. A SILICA-THICKENED GREASE HAVING ENHANCED WATER WASHOUTCHARACTERISTICS CONSISTING ESSENTIALLY OF A LUBRICATING OIL HAVINGINCORPORTED THEREIN A FINELY DIVIDED SILICA GELLING AGENT IN AN AMOUNTSUFFICIENT TO IMPART A GREASE-LIKE CONSISTENCY TO SAID LUBRICATING OIL,AND A COMPOSITE WATER-PROOFING AGENT CONSISTING ESSENTIALLY OF 410 PARTSBY WEIGHT OF (1) AND OIL-SOLUBLE MONO-ALKYL ETHER OF A POLYOXYALKYLENEGLYCOL PRODUCED BY REACTION OF A MONOHYDRIC ALIPHATIC ALCOHOL AND1,2-PROPYLENE OXIDE HAVING A MOLECULAR WEIGHT OF 800-1600 (ACETYLVALUE), AND ONE PART BY WEIGHT OF (2) AND OIL-SOLUBLE MONO-ALKYLARYLETHER OF A POLYOXYETHYLENE GLYCOL PRODUCED BY REACTION OF A C1-C18ALKYL-SUBSTITUTED PHENOL AND ETHYLENE OXIDE HAVING A AVERAGE MOLECULARWEIGHT OF 200-550, SAID WATERPROOFING AGENT BEING PRESENT TO THE EXTENTOF 9-10% BY WEIGHT OF THE SILICA IN AN AMOUNT SUFFICIENT TO IMPROVESUBSTANTIALLY THE WATER-WASHOUT CHARACTERISTICS OF SAID GREASE.